fake

attested in London criminal slang as adjective (1775), verb (1812), and noun (1851, of persons 1888), but probably older. A likely source is feague "to spruce up by artificial means," from German fegen "polish, sweep," also "to clear out, plunder" in colloquial use. "Much of our early thieves' slang is Ger. or Du., and dates from the Thirty Years' War" [Weekley]. Or it may be from Latin facere "to do." Related: Faked; fakes; faking.